In connection with electronic control systems for drive units of motor vehicles, the driver command for the longitudinal movement of the vehicle is detected. The driver command is primarily derived from the extent of the actuation of an operator-controlled element actuated by the driver. The operator-controlled element is, for example, an accelerator pedal. For this purpose, various solutions are suggested in the state of the art. German patent publication 196 19 324 discloses, for example, the determination of a desired value for a torque of an internal combustion engine in that a signal, which represents the accelerator pedal position, is interpolated between a changing maximum value and a changing minimum value. The maximum torque is then dependent upon the engine rpm, air pressure, air temperature, ignition angle setting, et cetera; whereas, the minimum torque includes: an output signal of the idle controller, the ratio of idle desired rpm and engine rpm, the loss torque because of inner friction of the engine in dependence upon engine rpm and the engine temperature as well as the torques which ancillary consumers consume for their operation and which do not contribute to the propulsion of the vehicle. In the illustrated embodiment of this known solution, the inner torque of an internal combustion engine (that is, the torque generated by combustion) is computed. For this reason, the minimum torque is set to the value zero when there is overrun operation.
U.S. Pat. No. 6,068,574 discloses another solution for determining the driver command torque. Here, the internal torque of the engine is not pregiven as the driver command but a torque which occurs at the output end of the transmission (wheel torque, transmission output torque, et cetera). Here too, a desired wheel torque is determined in dependence upon a signal representing the position of the accelerator pedal. Here, an interpolation is made between a maximum value of the wheel torque and a minimum value of the wheel torque. At least some of the described quantities are used to determine the minimum and maximum torques. By considering data as to the transmission ratios, which are present in the drive train, these torque values relate to the transmission output end torques.
From U.S Pat. No. 5,325,740, it is known to determine an output torque desired value or wheel torque desired value in dependence upon a signal, which represents the accelerator pedal actuation, as well as on the output rpm or vehicle speed.
The known ways for processing the driver command are directed exclusively to the objective of controlling the engine. For this reason, there is an optimizing requirement with respect to the processing of the driver command for other control systems such as for a transmission or drive train control.
In the specific configuration of the driver command processing, it is of central significance that dead travel is avoided notwithstanding the scaling of the driver command torque.
With the formation of a predicted driver command torque based on the evaluation of a future possible drive train transmission ratio, the requirements of other control systems are also considered in the processing of the driver command. These requirements of other control systems are especially transmission controls or drive train controls and not only the control of the engine.
A clear task distribution of the driver command processing and another system (for example, a transmission control or coordinated drive train control) is made possible via the formation of driver command torque and predicted driver command torque and the output to an interface to other control systems. In this way, the driver command quantity can be determined centrally at one location so that other driver command processing in the vehicle for other control systems is unnecessary. A use of the accelerator pedal position as an input quantity is no longer necessary outside of the driver command processing.
It is especially advantageous when the driver command processing reads in information as to the state of the drive train, for example, from a transmission control unit.
In an especially advantageous manner, dead travel is completely avoided because of the consideration of the difference between the computed driver command torque and the minimum value or maximum value in the formation of the driver command torque notwithstanding the scaling of the driver command torque.
With the specific type of driver command formation, a driving behavior is made possible, which is independent in wide ranges from ambient influences. This is so because, in this range, a fixed relationship is present between accelerator pedal position and propulsion torque. A deviation from this fixed relationship takes place to avoid dead travel only in the proximity of the minimum and maximum values.
The application of the driver command formation is easily carried out so that the driver command processing can be flexibly adapted to different customer wishes.
In an especially advantageous manner, a distinction between the areas of overrun operation, idle or accelerative force with reference to the driver command processing is not necessary because the driver command torque formation covers all of these areas.
It is further advantageous that this driver command processing can be applied to all present day known drive concepts, for internal combustion engines, electric motors, et cetera. In this way, a torque-neutral shifting can be realized for all types of drives because the driver command torque is defined as a transmission output torque.